
Gass F 73 7 
Book Xx^/\l 



GLACIERS OF 
GLACIER NATIONAL PARK 





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"<=. - 



DEPARTMENT OF THE INTERIOR 

OFFICE OF THE SECRETARY 

1914 



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-^■^■^ GLACIERS OF GLACIER KATIO^tA^ PARK/ 

By AVm. C. Aldex, U. S. Geological Survey. 



INTRODUCTION. 

Glacier National Park derives its name and much of its interest 
from the presenc e of many small glaciers . Very much of the grandeur 
of its -wonderful Alpine scenery, the final sculpturing of the great 
mountain valleys and of the amphitheaters at their heads, and the 
production of the basins of its many beautiful lakes are due to the 
action of the more extended glaciers of the past. 

There are in the park about 90 small glaciers rangmg m size from 
Blackfeet Glacier, with its 3 square miles of ice, down to masses but a 
few acres in extent yet exhibitmg the characteristics of true glaciers. 
The most easily accessible of these from the beaten trails are the 
Blackfeet and Sperry Glaciers and the small glaciers at Iceberg Lake 
and at Ahern Pass. Some of the others can be reached by tourists 
who are willing to undergo the exertions of mountain climbmg. 
Among these are Grmnell, Chaney, Shepard, Vulture, and Carter 
Glaciers, and one or two at Brown Pass. (See map facing page 17.) 

After examining these features one can easily picture to himself, as 
he looks down the valleys, the great rivers of ice which m ages past 
cascaded from the cliffs below the upper cirques, converged as 
tributaries from the many branch valleys, and united m great trunk 
glaciers. In imagination he can see these great glaciers many 
hundreds of feet m depth filling the great mountain valleys from side 
to side, and deploying thence upon the bordermg plains. He seems 
to see these mighty engines plucking away the rock ribs of the moun- 
tains, smoothing, grmding, and polishmg theirregi-ilarities and sw^eepmg 
away the debris to be spread on the plams below. These glaciers 
developed and extended three times and, after each development, 
the congealed masses melted away on the return of milder clhnatic 
conditions, until at length only the small cliff glaciers of the present 

1 The descriptions of the glaciers and the discussion of the glacial phenomena presented in this paper are 
based upon studies by the writer, made during the summers of 1911, 1912, and 1913 for the United States 
Geological Survey, in and adjacent to the park. He was assisted in 1911 by J. Elmer Thomas; in 1912 by 
Eugene Stebinger, and in 1913 by Clifton S. Corbett. Xot all of the pricipal glaciers have been examined 
and much of the area of the park remains to be covered by the geological survey. The presentation in this 
paper is thus only preUminary in character and is intended rather as a popular than a technical discussion. 

For further treatment of the physiographic development of the region one should refer to the companion 
pamphlet issued by the Department of the Interior, entitled "Origin of the scenic features of Glacier National 
Park, Montana," by M. R. Campbell. This pubUcation may be purchased from the Superintendent of 
Documents, Government Printing Office, Washington, D. C, for 15 cents. 



4 GLACIEES OF GLACIEE XATIOXAL PAEK. 

day are left lurking in the protected recesses at the heads of the capa- 
cious valleys. 

Many of the rock-walled amphitheaters are no longer occupied b}' 
ice, but from all there issue streams fed by the meltmg snow or ice. 
These plunge over the cliffs m beautiful foaming cascades and rush 
on down the mountain gorges. The melting glaciers left many 
inclosed basms large and small, and m these the waters rest a while 
and mirror in their crystal depths the dark green of the surrounding 
forests, the rich colors of the rugged mountam walls, and the deep 
blue of the cloud-flecked sky. On again from lake to lake the waters 
flow and finally start down their long courses to the sea to merge at 
length with the chill waters of Hudson Bay, the balmy tides of the 
Gulf of Mexico, or the rolling billows of the Pacific. 

Compared in size with the great glaciers of Alaska the glaciers of 
Glacier Xational Park are msignificant. They are even surpassed 
in size by those of the Alps, of the Canadian Rockies, and of Mount 
Eainier, Washington. They are, however, though small, among the 
best examples of this mterestmg type of phenomena now existmg in 
the United States. They have also a splendid settmg in magnificent 
Alpme scenery, unsurpassed hi grandeur am-where. Hidden away 
in the recesses of the mighty mountam ranges these rare and won- 
derful features form a climax to many of the mterestmg trips open 
to the tourist. 

BLACKFEET GLACEER. 

General relations.— T\iq largest glacier of the park, one of the most 
readily accessible, and one exhibitmg m fijie development most of the 
features particularly characterizmg glaciers is the Blackfeet ^ (title- 
page and -?ig. 13, p. 21:). 

From Gunsight Camp, an easy trail leads southward about 1 mile, 
with an ascent of about 500 feet, to the foot of the main lobe of the 
western part of the glacier. Clmibing the morainal embankment 
which obstructs the view one looks out on a scene of surpassmg 
interest and grandeur. The distance across the glacier on a nearly 
east-west line, is 3.2 miles; the maximum extent southward from the 
front of the eastern lobe to the crest of the snow-covered Continental 
Divide on Blackfoot Mountam is 1.6 miles; the distance from the 
front of the western lobe to the divide southeast of Jackson Mountam 
is nearly the same; the approximate area of the entire mass is 3 sc[uare 
miles. Lying in a depression in the mountain slope, having a greater 
extent laterally than in the direction of movement, and havmg no 
lobate extension down the valle}^, it is what is known as a cliff glacier. 

1 In zn article in the Scientific American Supplement, Sept. 23, 1S99, George B. Grinnell states that in 
L891 he took to the head of St. Mary Eiver the first party that had ever visited it so far as kno-Rn. In 1895 
in company with a Government commission he again visited the head of the vaUey. In 1S97, in company 
with J. B. Monroe, he climbed Jackson Mountain, and in 1898 he ascended Blackfoot Mountain and from 
it beheld the glacier to the south which had been seen in 1SS3 by Prof. Raphael Pumpelly on a trip across 
Cut Bank Pass and which since that time has been known as Pumpelly Glacier. 



GLACIERS OF GLACIER XATIOXAL PARK. 5 

Banked against the upper mountain slopes is tlie snow field, or 
neve, from -wliicli the glacier originates. Here what is left of the snows 
of many winters has become compacted and changed to granular ice. 
When such ice accumulates to a sufficient thickness mternal move- 
ment begins. Such moving ice constitutes a glacier. High up on 
the slopes there may be seen, m places, a Ime of crevasses which 
marks a break between the movmg ice and the stationary part of 
the neve. Such a crevasse is called the ' ' bergschrund " by the 
Germans. The mam or eastern part of the glacier nearly fills the 
upper cirque extendmg almost to the crest of the cliff at the head of 
the valley southwest of Citadel Mounta.m. Beneath the western part 
of the glacier the slope nearly coincides with the inclination of the 
rock and there is no marked break forming a cliff. 

Moving do^^'n this slope, the ice of the western part of the glacier 
gathers m from all sides to a central stream. The lovv'er 0.7 of a mile 
of its extent is thus contracted to a narrow lobe about 1,600 feet in 
width. Tliis part is easily accessible to the tourist and here may 
be observed most of the typical characteristics of alpine glaciation. 

Moraines. — ^Uong the front of the glacier throughout nearly its 
whole extent is a great embankment or moraine of clay and bowlders 
which was formed by the piling up of rock debris carried forward b}^ 
the moving ice. The greater part of such material, wliich is known 
as drift, is embedded in the lower part of the ice when being trans- 
ported, but a smaller part is borne upon its surface, havmg fallen 
from the mountain slopes. TThen released by melting at the glacial 
front the drift accumulates and may be crowded up into a ridge. 
Much of the morainal material piled up along the front of the Black- 
feet Glacier probably accumulated some time ago when the ice was 
thicker and somewhat more extensive. A person standing on the 
moraine where it is most readily accessible from the trail sees the 
main lobe of the western part of the glacier extendmg do^sm between 
two great morainal embankments. The glacier thins to a frontal 
marghi at an elevation of about 5,725 feet above sea level. The 
moraines, however, continue some chstance farther do^^ii the slope 
and there they curve together and join in one continuous loop, show- 
ing that at some earlier date this lobe had a somewhat greater exten- 
sion. The distance from the end of the morainal loop to the front of 
the ice was not measured, but it is estimated as about 1,000 feet. 
Across the end of the loop trees are growing, but nearer the ice there 
is no vegetation and the bare slopes are very steep and in places 
even precipitous as the result of slumping and shding of the clay and 
bowlders. The moraine ranges in height from 20 to 100 feet Tsdth an 
uneven, ridged crest varpng from a few feet to a few yards in \sidth, so 
that it is a striking topographic feature. For some distance from the 
lower end of the ice lobe the northwest margin has been melted back 
50 to 100 yards, from the foot of the inner slope of the moraine, expos- 



6 GLACIEES OF GLACIER XATIOXAL PARK. 

ing the bare, smoothly pohshed, and striated ledges of rock over 
which the ice formerly extended. Farther west up the slope the thin 
ice extends to the foot of the moraine. On the east side of the lobe 
the ice extends to the foot of the moraine but the crest of the latter 
towers high above it. 

Movement. — That the ice is not stagnant but moving slowly forward 
may be easily demonstrated. Opposite the sharp curve in the moraine 
at about 6,350 feet above tide there is a change in the slope. Looking 
into a low ice cave at this place one can see far under the glacier. 
Here the ice after passmg the crest of the ledge extends free a few 
feet above the rock over an area of man}- square rods before breaking 
doTsai. An iron spike set in the ice at this place on August 19, 1913, 
showed a movement of 3^ inches in the fu'st 24 hours, of thi^ee-eighths 
inch in the next 5 hours, and of 3| inches in the succeeding 25 hours 
and 25 minutes. This gives an advance of 7 inches in 54 hours and 
25 minutes. 

0^^dng to the steepening of the slope at this place the ice is much 
crevassed. Some distance farther up the slope is another broad 
zone in which the ice is much broken b}- crevasses. A second spike 
set in the ice wall of a cavity at a point N. 85° W. of the peak of 
Jackson Mountain, and about 6,725 feet above tide near the lower 
border of the upper crevassed zone, showed an advance of 1| inches 
ia 24 hours, and in the succeeduig 30 miQutes an additional advance 
of one-eighth hich, the time being m the middle of a warm, bright 
day. 

On August 21, a marked pebble was set in the ice at a point in 
front of the glacier JST. 75° E. of the peak of Jackson Mountain and 
six-tenths of a mile northeast of the 6,S79-foot bench mark. The ice 
at this point advanced seven-eighths mch ui 4f hours during the warm 
part of a warm day. 

This is a crude method of measuring the rate of movement, and the 
results can not be regarded as a true index of the rate ui all parts of 
the glacier. No attempt has yet been made to obtain accurate 
measurements of the movement in tliis or any other glacier within 
the park, and no estimate of the total 3^earl3- advance can be made 
from measurements as few and so crude as these. The rate of glacial 
movement varies greatly with temperature and other climatic condi- 
tions, being more rapid on warm moist da^^s than on cold and dry 
days.^ 

Crevasses and ice cascades. — Ice has little elasticity, so that crevasses 
are produced in the surface of a glacier b}- tension at places beneath 
which are considerable uTcgularities or steepenings of the rock slope 
down which the ice is moving. As the broken ice mores slowl}' forward 

1 The rates of average daily movemeBt of glaciers in the Canadian Rockies and Selkirks range from 2 
to 20 inches, of the great Alaskan glaciers 1 to several feet, as much as 7 feet on Muir Glacier. In the Swiss 
Alps the rates range from 1 or 2 inches to 4 feet or more per day. 



GLACIEES OF GLACIEE XATIOXAL PAEK. i 

a succession of fractures constantly takes place in tlie same relative 
positions. There is a regailar cycle in tlie development of crevasses 
which is well illustrated in the upper crevassed zone on the west- 
ern part of Blackfeet Glacier (title-page). In the upper part of the 
central belt the cracks appear; farther do^^-n the widening of the 
cracks by melting breaks the surface into fiat-topped tables. As the 
crevasses gradually ^^uden the intervening tables narrow until they 
become sharp-crested ridges where one can scarcely find footing. Fol- 
lowing this the sharp ridges may be broken mto pumacles or seracs, 
such as may be seen at one place near the ice front south of Citadel 
Mountain. Finally the ridges are lowered by the melting and gradu- 
allv disappear. With the closing of the crevasses below, the surface of 
the glacier thus becomes again smooth and passable. Crevasses are also 
sometimes healed by bemg filled with snow or by the freezing of water 
which may accumulate in them when the bottoms are tightly closed. 
From the latter result the ice dikes seen on some of the other glaciers. 

These crevasses are dangerous pitfaUs in the way of the tourist, 
even when not treacherously hidden by a slight covering of snow. 
TTith competent guides and care, however, the less fractured parts of 
the glacier may be traversed in safety. 

At many points on the higher slopes the snow and ice may be seen 
cascading over the ledges. Here the ice is greatly crevassed and 
broken and great masses stand ready to fall, especially on warm days. 
Such cascades, though very attractive, are dangerous to approach. 
On the slope of Blackfoot Mountain (fig. 13, p. 24), where a great 
ledge intervenes, the continuity of the cascade is broken for some 
distance by a cliff of bare rock, above which rises a cliff of ice. Here 
the ice, which is pushed forward above the cliff, may break off and 
drop to the glacier below, there to be welded by refreezmg into the 
continuous sheet. 

Structure. — The ice composing a glacier is generaUy stratified in 
layers as a result of the conditions of original deposition. This struc- 
ture may be indicated by more or less definite dht zones extendmg in 
parahel curving lines across the surface of the glaciers. As the layer 
of snow which accumulates during one whiter is gradually thinned or 
melted away during the succeeding summer, dust and smah rock 
fragments which have fahen upon it become concentrated in a thm 
but fairly definite layer. This is later buried beneath the clean 
snows of the fohowing winter. When compacted to glacier ice, there- 
fore, there are apt to be thm layers of somewhat dirty ice alternathig 
with thicker clean layers. In places where the surface of the snow 
does not become soiled by rock debris, meltmg may cause the forma- 
tion of a crust of nearly clear ice which, when buried by later snows, 
appears as a blue band. . The thicker intervening layers appear white 
because the unfiUed air spaces between the ice granules permit refiec- 
tion of light from the myinad surfaces. The beautiful banded 



8 GLACIEES OF GLACIER NATIONAL PARK. 

structure of alternating blue and white ice may be seen in the sides 
of the crevasses. As the glacier is thinned by melting, these layers 
outcrop as zones in the frontal slope. They correspond, in a way, to 
the annular rings in the growth of a tree. 

Drainage. — During the cool nights and early mornings there is 
little sound of water on a glacier, but as the day warms Httle rivulets 
begin to flow on the surface of the ice ; where there is much crevassing 
the water finds its way quickly to the base of the glacier, and there it 
may be heard rushing down the slope. From the front of the ice 
there flow rushing streams white with silt from the rock ground fine 
beneath the glacier, the ^^gletschermilch" of the Germans. The main 
or eastern part of Blackfeet Glacier is somewhat less crevassed and 
more water flows in rivulets upon the ice. These unite to form 
streams a foot or two in width, but of high velocity, since the surface 
of the glacier has toward the front a 15° slope. The sharply sinuous 
channels cut in the ice reach, in places, depths of 20 to 35 feet. At 
one point a stream was seen plunging down a vertical well, or moulin, 
to join the subglacial flow. The depth of such a hole might be 
measured to ascertain the thickness of the ice. 

Work of tlie glacier. — The work of such a glacier as that being 
described is manifested in the production of the cirque or amphitheater 
which it occupies, in the abrasion of the rock floor over which it 
moves, and in the deposits resulting from the drift which it produces 
and transports. 

The greater part of the rock composing the mountains of the park is 
stratified in layers, mostly thin, but ranging in thickness from a 
fraction of an inch to 30 feet or more. The strata are generally 
broken at frequent intervals by cracks or joints, and water percolating 
into these crevices expands on freezing and forces the pieces apart. 
Alternate freezing and thawing breaks up and loosens the fragments 
ready to be removed. Many fall or are carried Aowji from the cliffs 
and upper slopes by avalanches of snow. Others beneath and 
behind the glaciers become frozen in the moving ice and are plucked 
from their places and slowly carried away. The ice always advances 
and never retreats, so that as long as the glacier exists, unless it 
becomes absolutely stagnant, material is continually bemg removed. 
A glacier may thus be said to gnaw continually at the slope and eat 
its way back into the mountain. 

Some geologists maintain that the breaking up of the rock and the 
plucking away of the loosened fragments is particularly facihtated by 
changes in temperature in the air and the water admitted by the 
yawning bergschrund which is so often seen in the neve at the back 
of the glacier. Continued sapping steepens the .walls until the great 
amphitheaters or cirques are produced. The Blackfeet Glacier does 
not occupy such a deep and symmetrical cirque as is seen at many 



GLACIEES OF GLACIEE XATIOXAL PAEK. \) 

other places iii the park. It is probable, however, that this is still 
being extended back into the momitam slope. 

Only a relatively small amount of rock debris falls from the upper 
mountain slopes onto the Blackfeet Glacier, and there is little or no 
drift seen embedded m the ice exposed in the sides of the crevasses, 
neither is any bemg carried by the surficial streams. Lookuig uito 
caverns under the ice, one sees here and there pebbles and bowlders 
at or in the bottom of the ice, and the undersurface is coated with a 
thin layer of mud, the product of the grmdmg of the fragments and 
of the'^rock bed beneath the glacier. One sees also the smoothed, 
pohshed, and striated rock surface extending back beneath the base 
of the moving ice. A glacial cparry was observed m the upper part 
of the bared space between the northwest margm of the Blacldeet 
Glacier and the moraine. Here the ice has evidently plucked loosened 
blocks from the exposed edges of the strata as quarrymen remove 
layer from layer in the process called stoping. Many blocks derived 
in this way are found incorporated in the moramal embankments. 
Some of the blocks are but little worn, as though transported on the 
surface of the ice, but most of them are subangular v^ith polished and 
striated facets, showing the effects of abrasion beneath the glacier. 
Much of the morainal material is fuie rock flour. The whole con- 
stitutes a heterogeneous deposit of unassorted glacial till. Sharp 
morainal embankments border nearly the whole frontal margin of 
the Blackfeet Glacier (fig. 13, p. 24\ 

Former extent oftJte glacier. — The marginal lobes of the main eastern 
part of this glacier, like the western lobe, are somewhat shrunken 
from their morames, an indication that some time ago the ice had a 
greater extension. 

On the slo^^e between Gunsight Camp and the glacier the surface 
of the limestone is in most places somewhat roughened as a result 
of etching by solution by the water flowing over it. In places, 
however, the surface is smooth, polished, and scratched the same as 
the rock surfaces -^^ithin the moraines. This indicates that at some 
time the glacier extended beyond the limits now marked by the mo- 
raines. Shnilar glaciated surfaces are found far down St. Mary 
Valley, and the valley bottom and lower side slopes carry glacial 
drift quite to the international boundary, a distance of 38 miles from 
the divide at Blackfoot Mountain. Such drift extends up the slope 
east of Lower St. Mary Lake nearly to o.SOO feet above tide; i. e., 
1,300 feet above the lake. Drift was also found on the slope of 
Singleshot Mountain west of Upper St. Mary up to an elevation about 
1,200 feet above the lake. Moreover, that part of St. Mary Valley 
within the mountains has not the sharply cut V-shaped transverse 
profile of a stream-cut mountain gorge, but has the broadly rounded 
U-shaped profile typical of a glaciated valley. Tributary to St- 
36592^—14 2 



10 GLACIEKS OF GLACIER NATIONAL PAEK. 

Mary Valley above the lower lake are more than 25 cirques^ which 
formerly contained glaciers. From such evidence it is apparent that 
the whole St. Mary Valley as far down as the international boundary 
was once occupied by a great glacier, of w^hich Blackfeet Glacier and 
17 other smaller glaciers remain as the only representatives in this 
part of the park. (See map facing page 32.) The contours of the 
valley indicate that the great St. Mary Glacier must have had a 
thickness of 2,000 to 2,500 feet where is now Upper St. Mary Lake. 
Glacial modification of St. Mary Valley. — Figure 1, A and B, which 
is based on the contours of Swif tcurrent Valley, illustrates the differ- 
ence between a stream-cut mountain valley and the same valley after 
it has been subjected to vigorous glaciation. In the paper by Mr. 
M. R. Campbell on the origin of the scenic features of the park, it is 
pointed out that the formation of the great mountain valleys was 




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A. B. 

Fig. 1.—^, Sketch of stream-cut valley; B, sketch op same valley after 
modification by glaciation. 

due primarily to the work of streams which cut deeply into the moun- 
tain mass. When climatic conditions became such as to result in 
the vast accumulation of snow great glaciers developed in each of 
the moimtain valleys. As the glaciers gradually extended all of the 
loose rock debris which had accumulated on the lower part of the 
slopes and at their feet became frozen into the base of the ice. Par- 
tially loosened blocks were also plucked away bodily and moved 
forward down the valleys. A mass of ice 2,000 feet in thickness 
exerts a pressure of 56 tons per square foot on the bed upon which it 
rests. The rock-shod ice thus became in effect an enormous rasp, 
which scored and polished and wore away all the minor irregularities 
of the slopes and bottoms of the valleys. Such enormous masses 
of moving ice do not adjust themselves to the sinuosities and irregu- 
larities of the valleys as readily as does water in its liquid state. In 
consequence of this and of the enormous weight of the moving mass, 
every opposing ledge and mountain spur were subjected to vigorous 
abrasion; the valley bottom was broadened and the side slopes were 
steepened until the whole became a broad open trough. 



GLACIEES OF GLACIER XATIOXAL PAEK. 11 

The attitude of the rock strata and the resistance which they 
offered to removal as a consequence of differences in hardness or in 
massiveness of bedding determined in some degree the depths to 
which the yalley was deepened in various parts. Thus a particuhirly 
resistant stratum, such as the massive ledge of limestone which crosses 
St. Mary Yahey at the narrows in Upper St. Mary Lake, was not 
worn away to the same extent as were the softer rocks farther down 
the valley or the thinner-bedded rocks above. Broader basins were 
thus developed above and below this ledge, and when the ice melted 
away these basins were filled ^\'ith water, forming a lake. The failure 
to cut as broad a channel through the limestone ledge caused the 
constriction or narrows in Upper St. Mary Lake. In some of the 
other valleys, such as Swiftcurrent Valley, a lake was formed above 
the ledge, but no channel was cut through, so that the escaping waters 
plunge in a foaming cascade over the obstruction to the valley below. 
Moraines and other deposits of drift were left on the melting of the 
great valley glaciers, and in some places lakes, such as Bo^vman Lake 
and Quartz Lake, are due, in part at least, to the blocking of the 
valleys by such accumulations of drift. 

HARRISON GLACIER. 

One of the interesting trips from Gunsight camp is southwestward 
up the smooth, snow-covered surface of the upper western part of the 
Blackfeet Glacier to the crest of the Continental Divide in the notch 
southeast of Jackson Mountain. Looking westward from this point 
one gets a magnificent view of the cascading lobes of Harrison Glacier 
(fig. 2). The main glacier, which lies high in the upper northern part 
of the great cirque at the head of Harrison Creek, is seven-tenths of 
a mile wide from east to west and nearly a mile long from north to 
south. From this a series of ice lobes spill over and cascade down 
the steep slope to benches in the great cirque wall. Of these the one 
nearest the observer and the one farthest away appear to extend to 
well-marked moraines, the one near by does not reach the highest 
and outermost of the ridges, but ridged drift is spread over the space 
between the ridge and the ice front. The front of the fourth is some 
distance back from the end moraine, from which two finely developed 
laterals extend up the slope. The fifth lobe breaks off at the top of 
a cliff over which its morainal material is pushed. 

SPERRY GLACIER. 

General relations. — High up in the upper cirque at the head of 
Avalanche Basin hes Sperry Glacier ^ (fig. 12, p. 24) . This is next in size 
to Blackfeet Glacier, having a maximum width at the front — i. e., from 

1 In January, 1896, there was published in Appalachia (Vol. VIII, pp. 57-69) an article by Lyman B. 
Sperry on Avalanche Basin, Montana Rockies, in which he described explorations of this lasin made in 
May and July, 1S95, by a party of which he was a member. An effort was made at this time to reach the 
upper cirque and find the source of the waters which were seen to be milky with glacial silt. It was not, 
however, until 1S96 that Dr. Sperry succeeded in reaching the glacier which now bears his name. (See 
Glaciers in the Montana Rockies, by L. W. Chaney, jr., Science, new ser., Vol. IV, pp. 761-762, 1S96.) 



12 



GLACIEES OF GLACIER NATIOXAL PAEK. 







GLACIEES OF GLACIER XATIOXAL PAEK. 



13 



northeast to southwest — of 1^ miles — and a length — i. e., from north- 
west to southeast — of about 1 mile. Its area is estimated as about 1 
square mile. The great cirque at the head of Snyder Creek between 
Edwards Mountain on the south and Mount Brown on the north was 
excavated so far back into the mountain mass that the upper part of 
the divide between Snyder Valley and Avalanche Basin was cut 
away, leaving a broad notch between Edwards Mountain and the 
small pyramidal peak known as Little Matterhorn. Through this 
col some of the water from the eastern part of Sperry Glacier goes 
to Snyder Creek. A similar notch was also developed between 
Edwards Mountain and Gunsight Mountain. It is through this 
latter notch that the trail climbs from the creek at the crossing: below 




Fig. 3. — Moat at east side of Sperry Glacier, showixg stratification in 
the ice wall on the right. 

Photograph by ^Y. C. Alden. 

Sperry Camp, about 6,200 feet above tide, to the southwest side of 
the glacier at 7,700 ± feet above tide. 

The surface of the ice is for the most part smooth and not crevassed 
and may be crossed in any direction. With care one may also de- 
scend the slope to the frontal margin. At the southwest side, the 
front is about 450 feet lower than the top of the iron ladder. It is 
at and near the front of the ice that the most interesting phenomena 
are to be observed. 

Structure. — In the front slope soiled zones mark the outcroppmg of 
the dirty surfaces of successive ice strata, each the residuum of one 
or more year's sno^vfalL Other than this the surface of the glacier is 
almost entu-ely clean of debris excepting on the lower part of the 
frontal slopes immediately adjacent to the ice margin where there is 
a scattering of pebbles and bowlders with a little clay. The stratifi- 



14 



GLACIERS OF GLACIER NATIO^^AL PARK. 



cation may also be seen in the sides of the few open crevasses. The 
best view, however, of the bedded structure of the glacier is to be 
had where the east side of the glacier rounds a salient of the cu-que 
wall at a pomt about two-fifths of a mile south-southeast of the front 




Fig. 4. — Sperry Glacier, bergschrund on slope of 
Edwards Mountain. 

Photograph by W. C. Alden 

of the most easterly marginal lobe of the glacier. On the northwest 
side of the point of the salient instead of the ice crowding against the 
rock slope there is a great chasm, or moat (fig. 3), one side of which 
is formed by the rock wall. The other is a smooth, curving wall 
of stratified ice, 150 feet or more in height. This moat is probably 



GLACIERS OF GLACIER XATIOXAL PAEK. 15 

due, in part, to the fact that the ice passing the rock salient does not at 
once spread later ahy after passing the point. The lower part of the 
cliff thus exposed is warmed by the afternoon sun and radiates a cer- 
tain amount of heat which, meltmg the ice, tends to prevent its closing 
up the moat until it has passed on some distance around the point 
or may even actually enlarge it. The water resultmg from the meltmg 
escapes laterally beneath the glacier so that the moat, at least when 
visited by the ^^Titer in August, 1913, contahied no stream or ponds. 
Ice caves and glacial movement. — In the upper part of the neve on 
the slope of Edwards Mountam a bergschrund (fig. 4) yawns as the 
result of the ice moving away from the mountam slope. At several 
points along the front of the glacier there are smaU caverns. Instead 
of breaking do^^Ti immediately after passmg the highest part of a 
ledge, the ice projects forward as an arch fluted in correspondence 
with the inequalities of the ledge surface. One such ice cave 
was seen into which a person could walk a distance of 50 or 60 
feet from the entrance, and probably one could proceed an equal dis- 
tance farther if disposed to crawl on his hands and knees on the wet 
rock. In these caverns the fact that the ice is really in motion may 
readily be demonstrated. Markers were placed in the ice walls and 
upon the ledges, and the distance between the marker in the ice and 
that on the ledge was carefuUy measured mth the following results: 

Movement of ice in ice cave No. 1, at point S. 37° E. of Little Matterhorn. — 12.15 p. m., 
August 15, to 11.15 a. m., August 16; advance of one-fourth inch in 23 hours. 11.30 
a. m., August 16, to 10.25 a. m., August 17; advance of one-half inch in 24 hours. 10.30 
a. m., August 17, to 11.15 a. m., August 17, advance of one-eighth inch in 45 minutes; 
11.15 a. m to 4 p. m., advance of one-eighth inch in 4f hours. 

Movement of ice in ice cave No. 2 at point S. 43° E. of Little Matterliorn. — Xoon, Au- 
gust 16, to noon, August 17, advance of one-half inch in 24 houi's. 

Movement of ice in ice cave No. 3, west side of middle ice lobe, at jwint S. 87° E. of Little 
Matterhorn.— 1.1b ^. m., August 16, to 1.15 p. m., August 17, advance of three-fourths 
inch in 24 houi-s. 

Movement of ice in ice cave No. 4 at west side, of eastern ice lobe at point S. 45° E. oj 
Heavens Peah. — 2.30 p. m., August 16. to 2.30 p. m., August 17, an adA'ance of about 
one-haLE to thi-ee-foui-ths inch in 24 houi's; markers loosened by melting. 

The measurements have not been continued over a sufficiently long 
period to warrant basing upon them an estimate of the average daily 
or total yearly advance. The measurements made in cave Ko. 1 
show the variations in the rate of motion due to difference in tempera- 
ture. On the first day, August 15, when the weather was cold and 
blustering, with some snow falling, an advance of but one-fourth inch 
was noted. During the follo^^-ing 24 hours the weather became bright 
and warm, there was much melting of the ice, and the advance noted 
then was one-half inch. 

Moraines. —"YhQ front of the glacier is bordered by well-marked 
terminal moraines. These are sharp, narrow, and uneven-crested 
embankments 20 to 50 feet in height, composed of intermingled clay. 



16 



GLACIERS OF GLACIER ITATIONAL PARK. 



or rock flour, pebbles, and bowlders. Generally there is an interval 
of a few rods between the ice and the main ridges, showing that the 
glacial margin has retreated somewhat since the formation of the mo- 
raine. The foot of the glacier, for the most part, rests on nearly bare 
rock, but in one place it appears to lie on top of a morainal accumula- 
tion nearly 50 feet in height (fig. 5). Here one sees the moraine in 
process of construction. It is possible that the drift here merely 
covers the margin of the glacier so that the core of the ridge is of ice- 
The southwest half of the glacier is underlain by banded red and 
white quartzite and argillite, while the floor of the northeast half of 
the cnque is composed of the grayish to buff limestone. As a result 
the southwest half of the terminal moraine is composed principally of 




Fig. 5. — Moraine at front of Sperry Glacier. 

Photograph by W. C. Alden. 

maroon-red argillite and quartzite, and the water in the brooks and 
morainal ponds is reddish from the silt held in suspension. The 
northeast half of the moraine, on the contrary, is composed mostly 
of grayish limestone, and the water of the ponds and streams issuing 
here is white, the typical ^^gietschermilch." 

At two places marginal lobes of the ice project forward in trough- 
like depressions in the rock floor of the cirque. Where these ice- 
tongues occur the moraine bends sharply and extends parallel to the 
sides of the lobes as lateral moraines. These laterals are connected 
in a large loop about the end of each ice lobe. 

A short distance outside the inner morainal belt is one of earlier 
formation disposed in loops indicating that the ice margin was for- 
merly somewhat more lobate than at present. This outer moraine 
is subdued in contour, the irregularities of crest and slope having been 



GLACIEKS OF GLACIER XATIOXAL PARK. 



17 



partially washed away, and is covered iii part by a scanty growth of 
dwarfed trees. 

Bock scoring and plucHng. — In the ice caverns the observer gets an 
excellent idea of the abrasive work done by the glacier. The surface 




Fig. 6. — Glaciated groove near front of Sperry Glacier. 
Photograph by W. C. Alden. 

of the bed rock is beautifully smoothed, polished, and striated. This 
surface is seen to extend back under the moving ice whose under- 
surface is plastered with a thin coating of wet mud or rock Hour, and 
set \\ith fragments of rock. This is the abrasive material with Avhich 
the work is done. There seems to be no considerable amount of 
36592°— 14 3 



18 GLACIERS OF GLACIER NATIONAL PARK. 

gravel or rock fragments in the base of the ice, as removal of the sub- 
surficial coating shows clear, clean ice above. Here may be seen 
how the icC; melting under pressure against inequaUties of the rock 
surface, is fluted with grooves corresponding to those irregularities, 
while at the same time all the small projections are being worn away. 

Not only does the surface of the rock floor of the cirque wdthin the 
moraines show the effects of glaciation, but between the outer moraine 
and the lip of the cirque, below which the great cliff drops to form the 
head of Avalanche Basin, the rock is smoothed, poUshed, striated, 
and grooved in a remarkable manner. In places the ice has been 
forced along more or less tortuous grooves, which were probably first 
worn by water running beneath the ice (fig. 6). 

The method of glacial quarrying known as plucking is also w^ell 
illustrated. At one place east of Little Matterhorn the striated floor 
is cut by a vertical northeast-southwest joint face. Beyond this a 
lower level was in process of being developed by stoping when the 
ice was melted away. Some great blocks of rock 10 by 15 by 20 feet 
in size have been loosened along the joints and moved distances 
ranging from a few inches to several feet. Others have been moved 
50 to 100 yards or more and left stranded betw^een the quarry face and 
the lip of the upper cirque. Still others, doubtless, were forced on 
over the cliff to be dashed in fragments on the ledges below. x4.t one 
point the opposed faces of a joint, now 3 to 5 feet apart, are striated 
in a direction transverse to that of the striae of the main ice movement 
on the floor above as though the basal ice had squeezed laterally into 
the crack and gradually forced the block on the northeast away from 
its original position. One joint but a few feet back from the crest 
of the cliff at the head of Avalanche Basin has been broadened 
several feet to a considerable depth. Had the disrupting action 
continued but a little farther a great mass of the upper part of the 
cliff would have been tipped over into the great cirque below. It is 
largely by such processes of glacial plucking or stoping that the 
great cirques have been excavated. It seems probable that only a 
subordinate amount of material was removed by abrasion beneath 
the great rasp formed by the rock-shod ice. 

Former eoctent of the glacier. — The relations are such that there can 
be no doubt that in comparatively recent time, geologically speaking, 
though thousands of years ago, Sperry Glacier not only occupied the 
whole of the upper cirque but filled Avalanche Basin and was con- 
fluent with a great glacier in the canyon of McDonald Creek (see 
map facing p. 32). 

At its southw^estern end the terminal moraine is near the crest of 
the cliff at the head of Snyder Creek. Some of the water from the 
western part of the glacier flows over this cliff. The trend of the 
strise outside the moraine also indicates that some of ih& ice formerly 
passed through the gap between Edwards Mountam and Little Matter- 



GLACIEES OP GLACIER NATIONAL PARK. 19 

horn and joined a glacier in Snyder Creek Valley. It is also probable 
that some of the ice went through the gaps between Edwards Moun- 
tain and Gunsight Mountain to a glacier in Sprague Creek Valley. 

All over the rock sheK on which stands Sperry Camp and on the 
ledges along the trail to Sperry Glacier there is a fine exhibition of 
the polishing and striating action of the glacier which formerly 
occupied the valley. Striae on some vertical faces beside the trail 
slope steeply, in places nearly or quite vertically, showing how the 
ice descended from ledge to ledge. 

SWIFTCTJRRENT GLACIERS. 

Grinnell Glacier. — The largest of the giaeiers at the heads of tribu- 
taries of Swiftcurrent Valley is the Grinnell Glacier, so named in 
honor of Mr. George B. Grinnell, one of the first to explore these moun- 
tains. This occupies the upper cirque on the north side of Gould 
Mountain. From Sherburne Lakes, 10 miles distant, the white and 
glistening glacier may be seen nestling at the foot of the Garden 
Wall in the cirque between Gould and Grinnell Mountains. While 
not so readily accessible as some of the other glaciers this one can be 
reached from Many-Glacier Camp by going up Cataract Creek trail 
along the west shore of McDermott Lake and then climbing up and 
along the south slope of Grinnell Mountain (figs. 7 and 8), or one may 
get a fine view of it from above by a climb from Granite Park to a 
notch in the Garden Wall. 

This glacier has a width from northwest to southeast of about 1| 
miles and a length from southwest to northeast of about 1 mile. 
Its area is a little over 1 square mile. It consists of a neve-covered 
upper part, lying on an upper bench in the western part of the cirque, 
and the main glacier, whose lowest point is not far from the crest 
of the cliff which rises abruptly nearly 1,000 feet from the valley 
floor above Grinnell Lake. Through most of its lateral extent the 
upper mass of ice ends at the crest of the bare rock ledge below the 
upper bench. South of this, however, the ice cascades over the ledge 
with a much crevassed surface to the main glacier below. From the 
encircling cliffs the ice flow converges toward the lowest point in the 
lip of the cirque. A large part of the surface is crevassed, showing 
that the ice is moving down over an uneven bed, and nearly the whole 
surface is banded with the sofled zones which mark the outcropping 
of the ice strata. A morainal embankment, consisting of narrow 
sharp-crested ridges of drift 30 to 100 feet in height, closely borders 
the ice margin on the east and north. (Figs. 7, 8, and 9.) This is in 
part lateral and in part a terminal moraine. 

In a little niche at the side of a deep notch in the crest of the Gar- 
den WaU back of Gould Mountain, a thousand feet or more above the 
main glacier, is a fine example of a cliff glacier (fig. 8). This glacier 
is short and relatively thick. From the crest of the rock clift' its 



20 



GLACIERS OF GLACIER NATIOXAL PARK. 



nearly vertical face of glistening stratified ice rises 100 feet or more 
to the smoothly rounded, snow-covered crest (fig. 10). 

On the north side of Grinnell Mountain lies another small glacier on 
a rock shelf at the top of a 1,500-foot cliff. This is in view of tourists 




Fig. 7. — Gould Mountain and Grinnell Glacier. 

Morainal ridge at left and in foreground. 
Photograph by T. W. Stanton. 

traversing the trail to Swiftcurrent Pass. The ice, which is much 
crevassed, extends to the crest of the cliff in places and dumps some 
of its morainal drift into the abyss below. 

In the next cirque north of Swiftcurrent Pass there is a notable 
development of steps or benches due to the stoping action in cirque 



GLACIERS OF GLACIEE XATIOXAL PAEK. 



21 



formation being carried on at several different levels. These are good 
examples of steps in a so-called '^glacial staircase.'^ There are two 




Fig. 8. — Grinnell Glacier, upper part, crest of moraine in foreground. 
Gem Glacier above at left. 
Photograph by T. W. Stanton. 




Fig. 9. — ^Moraine of Grinnell Glacier. 
Piegan Mountain in background. 

Photograph by 'J\ "\V. Stanton. 



of these benches in the upper part of the cirque, and on these lie four 
distinct little glaciers (fig. 11). 



22 



GLACIERS OF GLACIEE NATIONAL PAEK. 



Iceberg Lake and Glacier. — The charm of the view at the head of the 
North Fork of Swiftcurrent Creek lies in the combination of the 3,000-- 
foot, vertical, encircling wall of the amphitheater, the small glacier 
lying at its base, the beautiful little lake of deepest blue, and the daz- 




FiG. 10. — Front of Gem Glacier; on the Garden Wall 

ABOVE GrINNELL GlACIER. 
Photograph by T. W. Stanton. 

zling whiteness of the small icebergs usually floating in the lake (fig. 
14). With these masses of glacier ice there are usually cakes of lake ice 
floating even in August. Along the east shore of the lake is an '4ce 
rampart" of bowlders probably pushed up by the forward crowding 
of the ice when the lake is frozen over in the winter. 



GLACIEES OF GLACIER XATIOXAL PAEK. 



2a 



Crossing the shallow outlet stream one finds a way along the talus 
slope and over the ledge around the north shore of the lake. There 
is a considerable accumulation of angular and unworn rock fragments 
piled on the ice at the north side. This has evidently fallen from the 
cliffs and has been handled by the glacier only enough to pile up sharp 
morainal ridges 30 to 40 feet in height. Crossing these one reaches 




a o 



< o 
3 2 



the main part of the glacier (fig. 15), upon which there is also a sprink- 
ling of rock fragments. Toward the front the ice is broken by 
crevasses (fig. 16), and much of this drift must fall into these yawning 
cracks, and thus reach the base of the ice, there to be ground and 
polished beneath the moving glacier and pushed forward into the lake. 
In the ice walls of these crevasses the banded, stratified structure of 
the ice is well displayed. In that part south of the morainal ridge 
where seen by the writer, the banding is longitudinal, i. e., parallel to 




Fig. 12. — Sperry Glacier from Little M 

Photogra 





-^"^-^^ . 



*^^^^r 



•jCi'^/ 



Fig. 13. — Blackfeet Glacier, eastern part, Blac 

Photogra 



IHORX, GrXSIGHT MOUNTAIK IX BACKGROUXD. 
W. C. Alden. 




r MOUXTAIX AXD JaCKSOX MoUXTAIN IX^ BACKGROUXD. 
iV. C. Alden. 



26 



GLACIERS OF GLACIER NATIONAL PARK. 



the direction of the ice flow, and it is seen in the sides of the crevasses 
to dip southward at an angle of from 30° to 45°. In the front 
of the glacier this dip is seen to decrease southward and become nearly 
horizontal or slightly undulating and to extend thus across the glacier. 




Toward the south side the banding appears to curve again downward 
at a high angle which decreases again toward the south wall. 

The front of the glacier is now nearly a mile back from the crest of 
the cliff over which the trail climbs to the upper cirque. Striations 
on the rock ledges east of the lake show that at some former time the 
ice extended across and beyond the rock basin in which the lake now 
lies. Loosened and partially removed blocks of rock at and near the 
cliff between the lower valley and the upper cirque suggest the method 



rLACIEES OP GLACIEE XATIOXAL PAEK. 



27 




Fig, 15. — Feoxt of glacier at Iceberg Lake. 
Photograph by W. C. Alden. 




Fig. 16. — Glacier at Iceberg Lake showixg crevasses axd rock debris ox 

THE ICE. 
Photograph by ^Y .C. Alden 



28 



GLACIEES OF GLACIER XATIOXAL PAEK. 




Ill 

z o 2 

- r^ fcX' 

- -- o 

X Q o 



GLACIERS OF GLACIEE XATIOXAL PAEK. 29 

bv whicli the more extended moving ice was stoping back the cliff 
face when the melting of the ice ended the operation. 

Canyon CreeJc Glacier. — Above the beautiful lake at the head of Can- 
von Creek one may cross the alluvial fan and climb the steep slope of the 
moraine which is being built up by a small glacier. The glacier, which 
is almost covered with rock fragments fallen from the great encircling 
circpe wall, is considerably crevassed as though crowding f orvs^ard over 
the lip of the cirque. A still higher bench in the back of the cirque 
holds a small crevassed glacier and high up upon the west side in a 
niche above a projecting ledge is a third. 

Fanner extent oftlie ice. — The broadly rounded, U-shaped profiles of 
the valley (fig. 17), the oversteepened side slopes with small amount 
of taluSj the glaciated rock ledges, and deposits of glacial drift, to- 
gether with other general relations, indicate that during the last, or 
Wisconsin, stage of the glacial period, ST\-iftcurrent Valley and all its 
tributaries were occupied by a great glacier wliich was in turn tribu- 
tary to a former glacier which may be called the St. Mary glacier (see 
map facing page 32) . The small existmg glaciers described above are 
the dhninutive reimiants of this great stream of ice. The height to 
which Swiftcurrent Valley was filled by this glacier is not definitely 
kno^vn, but it probably reached 2,000 or 2,500 feet. High upon the 
mountain slope to the north, about 1,600 feet above the outlet of 
McDermott Lake, the writer observed rock ledges which had been 
polished and striated by ice moving eastward down the valley. Simi- 
lar striae were also seen on the northwest slope of Allen Mountain at 
about the same height above the lake. About 5 miles farther east 
where this glacier joined the trunk of the former St. Mary glacier the 
ice must have been at least 1.000 feet thick, judging from the eleva- 
tions of the morame which incloses Duck Lake, 3 to 6 miles east of the 
village of Babb. 

BELLY RIVER GLACIERS. 

Glaciers at Ahem Pass. — From Granite Park a trail leads northward 
to Ahern Pass. By this route one may cross the divide and descend 
Belly River Valley. From the pass down to the upper lake the trail 
is passable for pedestrians usmg caution but is not in condition for 
saddle or pack animals. August 22, 1S90, Lieut. George P. Ahern ^ 
led a party, consisting of a detachment of soldiers from the Twenty- 
fifth Lifantry, Mr. G. E. Culver and two prospectors, with packers, 
Indian guides, and a pack train, up Belly River Valley and across the 
pass which bears his name. 

One interestmg feature of this trail is that after passing the divide 
it leads down across the upper part of the slopmg surface of a small 
glacier and then passes out along the steep valley side, which is cov- 

1 Notes on a little known region in northwestern Montana, br G. E. Ctilver, Trans. Wis. Acad. Sci., 
vol. 8. pp. 1S5-205, 1S8S-01. 



30 GLACIEES OF GLACIEE NATIONAL PAEK. 

ered with loose sliding rock excepting where there are precipitous 
rock ledges. The surface of the small glacier descends steeply about 
500 feet to the crest of a chff which drops down thence 1,000 feet to 
the head of the valley below (fig. 18). Tlie angle of slope of the ice 
for several hundred feet above its foot is about 45°, and this steep 
slope is in part scored by open crevasses. It is not a suitable place 
for coasting. This glacier occupies a niche in the upper south wall of 
the great cirque just below the pass. The main head wall of the 
amphitheater is one of the most imposing in the park. The peak at 
its crest north of the pass stands nearly 3,600 feet above the upper 
lake. Of this the upper 2,500 feet stands almost vertical. Below 
this some small glaciers, with their neve banked against the base of 
the cliff, spread out slightly on the rock bench above the lake. These 




Fig. 18. — Glacier at Ahern Pass. 

Photograph by T. W. Stanton. 

are bordered by comparatively large moraines. One of these as seen 
from above surrounds the narrow end of the glaciers as a sharp V, 
like the nose of a snow plow (fig. 19.) Tlie ice appears to be thinned 
as the ridge stands up abruptly from its debris-covered surface. A 
short distance outside this is an earher moraine covered ^^ith vegeta- 
tion and encircling a pond of water. 

At the top of the vertical northwest wall of the cirque is another 
glacier about 2,600 feet above the lake. This hes 500 feet or more 
above the level of Ahern Pass so that only its front edge can be seen 
from that point. To one looking down upon it from the mountaui 
top above it appears as a considerable mass of ice with a \ndth from 
north to south of seven-tenths of a mile and a length from northwest 
to southeast of one-half mile. The frontal margin is pushed forward 



GLACIERS OF GLACIER NATIONAL PARK. 



31 



quite to the crest of the chff and in places appears to overhang so 
that the drift as it is thrust forward, and doubtless some of the ice 
also, falls over the precipice and the streams hang on the dark rock 
wall Hke silvery threads. 

Clianey Glacier. — From a camp on Flattop comparatively easy 
access to the glaciers at the head of Middle Fork of Belly River is 




Fig. 19. — Glaciers and moraines near Ahern Pass. 

Photograph by W. C. Alden. 

gained by chmbing to the notch in the crest of the mountain wall at 
the head of Mineral Creek. All five of these glaciers occupy scallops 
in the great upper cirque, above the tops of the cliffs against which 
head the main floors of the two branches of the Mddle Fork. 

From the notch, which is at about 7,950 feet above sea level, one 
sees Chancy Glacier spread out at his feet. This glacier was named 



32 



GLACIERS OF GLACIER NATIONAL PARK. 



ill honor of Prof. L. W. Chaney, jr./ of Carleton College, of Xorth- 
fielcl, Minn.; who visited it in 1895. 

Chaney Glacier (fig. 20) has a width from northwest to southeast 
of about 1 mile. From its upper edge, about 15 or 20 feet below the 



^ 




Hi 


''^^H 


m' 




■Hh 


lllBflH^ 



% ^ =:• 

3 3 1 



O 



=2 t 



notch in the divide, the smooth surface of the ice slopes northward. 
At the top the slope is gentle, but toward the front it is steeper, 
descending about 1,200 feet in a distance of one-half mile. At the 
north side of the eastern part of the glacier the ice extends as a nar- 
rowing tongue down into a notch in the lip of the upper cirque. 



Appalachia, Vol. VIII, 189&-1898. 






n 






:^& 






^ 






r4 



GLACIEES OF GLACIER NATIONAL PAEK. 33 

The smooth surface of the glacier is banded from side to side by 
curving zones of darker color. These are the soiled zones due to the 
concentration of dust and small rock fragments which accumulated 
on the surface of each successive mnter's snowfall. They thus dif- 
ferentiate the outcropping edges of the ice strata of which the glacier 
is composed. 

When seen by the vn-iter in 1911 and 1913 the ice was but very little 
crevassed, though a few cracks were open near the front of the lobe 
and in the upper part the latter were partially filled with snow. 
Interesting features seen in a few places were ice dikes 6 or 8 inches 
thick. These are formed by water freezing in the cracks, ^^lien 
subsequently there has been a little melting at the surface the parallel 
crystals may be raked out loosely mth a pick. Similar but radial 
structures are seen in several places where circular cavities several 
inches in diameter have been filled by ice crystals gro^\'ing converg- 
ently from the encircling ice wall toward the center of the cavity. 
Such features were called ^'gletschersternen/' or ^'glacier stars/' by 
Prof. Agassiz. 

About 250 yards below the notch in the divide by which the 
glacier is reached from the south there is a zone extending laterally 
part way across the glacier in which there are many ice wells or 
moulins. These are vertical holes m the ice varying in diameter 
from 1 to 6 feet. Many of them, especially those mto which stream- 
lets of water plunge after flowing on the surface of the ice, appear 
to extend to the bottom of the glacier. Others from which the 
streams have been diverted are partially filled \\dth snow. Sound- 
ings made by the writer in several of the wells ^\dth a cord and stone 
show depths ranging from 25 to 74 feet, the deepest being near the 
center cf the main ice stream. These are regarded as measures of 
the thickness of the ice at these several points, since it seems prob- 
able that the water descends to the rock floor of the cirque before 
flowing away beneath the ice. These wells are arranged in lines 
transverse to the direction of ice flow and appear to have been 
developed along cracks which now at least are tightly closed though 
visible. At points where cracks were opened across the course of 
rivulets, or where rivulets developed across cracks already opened, 
percolation of water down the cracks may have initiated the thaw- 
ing of holes which were gradually enlarged to their present dimen- 
sions. These wells were not noted farther down the slope in the 
central part of the glacier. It may be that along this zone is a posi- 
tion where successive cracks develop, though there are no open 
crevasses at this place. After one set of cracks and moulins have 
developed and moved a short distance down the slope the opening 
of new cracks in the former position may lead to the development 



34 GLACIERS OF GLACIEE NATIONAL PARK. 

of a new set of moulins, giving new apertures by which the water is 
diverted to the base of the ice above the former Hue of wxlls. Sub- 
sequently these latter may become filled wdth snow and contracted 
by pressure until no openings remain. In a direction somewhat 
west of north from the notch in the divide, at the west side of the 
main current to the frontal lobe of the glacier is a mound of buff 
argillite fragments. About the head or south side cf this are clus- 
tered many of these ice wells, so that this part of the glacier must be 
crossed with care. 

Near the west side of this mound was seen a larger hole about 15 
feet long shaped like a bathtub. This was filled with water to 
within a few feet of the surface and in the water floated a tiny ice- 
berg. This is a good example of the cavities designated '^ baignoires," 
or ''bathtubs/' by Prof . Agassiz.^ Soundings showed this '^ bath- 
tub '^ to be 12 feet deep. It is not evident what would cause the 
development of so deep a cavity in the ice, as it appears not to be 
due to running water, at least the bottom and sides are now so 
tightly closed that the water is retained. Possibly it was once a 
moulin like those farther up the slope, which after being abandoned 
by the stream of water became partly filled with snow and tightly 
closed by refreezing. Prof. Agassiz describes baignoires in which 
there is no debris as probably due to the closing up of crevasses. 

''Dust wells" are seen frequently. They are small vertical 
holes in the surface of the ice, a few inches in diameter, and a few 
inches deep with a little dirt at the bottom. At points w^here a 
small thin patch of dirt lies on the ice this dirt absorbs more heat 
from the sun than the surrounding ice and causes more rapid melting. 
Setthng of the dirt with the melting of the ice deepens the hole until 
it reaches the limit of depth to which the sun's rays can penetrate 
the cavity. 

The opposite, or protective, effect of rock debris upon the surface 
of the ice is well illustrated by the mound of rock fragments referred 
to above. This mound, which is 15 or 20 feet high, is probably 
principally of ice, but is completely covered by the rock fragments. 
Prof. Chaney 2 mentions such a '^ surface moraine of yellow slate/' 
evidently the same rock-covered ice mound, as having been seen by 
him in 1895. Apparently many years ago a mass of rock fell onto 
the ice from the cliff at the back of the glacier and mth the advance 
of the ice this has gradually moved forward. Meanwhile the sur- 
rounding ice surface has been lowered by melting while the ice I 
beneath the rock pile has been protected from melting. As the 
surrounding ice disappeared, rock fragments slid down the sides ofl 
the mound so as to cover the ice core. From this mound a belt ofl 
scattered drift extends forward like a medial moraine to the front] 
of the glacier. 

1 System Glaciare, 1847, p. 100. 2 Op. cit., p. 796. 



GLACIERS OF GLACIER XATIOXAL PARK. 35 

Excepting at the point of the lobe, the glacier is bordered b}- a 
strongly marked marginal moraine 20 to 30 feet in height. At the 
extremity of the ice tongue the drift has been pushed over the chff, 
though at present the ice is a short distance from the crest. One 
part of this moraine is largely composed of large and small fragments 
of lava (amygdaloidal trap rock). At a place west of the notch in 
the divide a bed of this rock extends to the top of the divide and 
there pelds fragments which fall onto the ice. Such lava blocks 
are scattered all the way across the glacier from the place where 
these blocks fall to the moraine. 

September 6, 1913, the writer attempted some crude measure- 
ments on the rate of movement in the glacier. On the west margin 
of the frontal lobe at a pouit about opposite the curve in the moraine 
a spike was set at 10.35 a. m. in the ice 45 niches m advance of a 
mark placed on the rock ledge. At 4.15 p. m. the distance, as 
nearly as could be determined, the spike having been shghtly dis- 
placed by melting, had mcreased to 45 J inches, an advance of one- 
eighth inch in 5 hours and 40 nunutes. This was at the side of the 
lobe where it would seem that the movement would be much less 
rapid than in the center of the stream. 

At a point near the extremity of the narrowed lobe a spike was set 
at 10.50 a. m. in the ice 37f iaches in the rear of a mark on the rock 
ledge. At 4.03 p. m. this distance had decreased to 37 J mches, 
iadicating an advance of one-eighth mch m 5 hours and 13 mmutes. 

Sue Lake and Glacier. — Going westward from Chancy Glacier past 
the spur of the mount am one finds a beautiful httle lake of blue lying 
ia a rock basin in the next scallop of the great cirque. At the head of 
the lake is a tiny glacier Ipng at the foot of the great circjue wall. A 
strongly marked morame 30 to 40 feet high borders the front of the 
ice at the edge of the lake, excej^ting for an interval where a narrow 
tongue of the ice projects through and into the lake. From this 
ice small bergs break off and float in the lake. A narrow chff glacier 
hes on a bench m the south wall high above the lake. The outlet 
stream from the lake flows a few rods over rock ledges and then 
plunges 300 to 400 feet down the cliff to a lower compartment of the 
great cirque. 

SJiepard Glacier. — Crossiag the creek which flows from Sue Lake 
and chmbmg over the ledges west of the outlet one reaches Shepard 
Glacier (fig. 21). This glacier was named for E. K. Shepard, of 
Mmneapolis, who visited this region ki company mth Prof. L. W. 
Chaney ia 1895 and subsequently. 

This small glacier has an extent from northwest to southeast of 
about one-half mile and from southwest to northeast of about three- 
tenths of a mile. It occupies two levels of the cirque, the northern 
part being divided by a rock cliff. The mam part cascades over 



36 GLACIERS OF GLACIER NATIONAL PARK. 

this cliff and in so doing is broken by great yawning crevasses which 
are closed again in the steeper slope below. 

The front of each of the northern arms of the glacier is bordered by 
a morainal embankment, for which there is barely room at the tops 
of the chffs. At the south side of the main glacier is a moraine piled 
5 to 25 feet high. In places the ice margin is melted back 50 to 70 
feet from this moraine. The dirt bands marking the edges of the ice 
strata show plainly. From the lower ice front a stream of water 
plunges several hundred feet down the cliff to the lower cirque floor. 

Glacier southeast of CJianey Glacier. — Across the mountain wall on 
the southeast side of Chancy Glacier is another small glacier poking 
its nose into a little lake, which lies in a rock basin behind the lip of 




Fig. 21. — Shepard Glacier. 
Photograph by W. C. Alden. 

the upper cirque. When seen by the writer from the top of the 
cirque wall in August, 1911, this lakelet was dotted ^\dth floating 
masses of ice which had broken off from the glacier front. The 
water which overflows the lip of the cirque plunges 1,500 feet to a 
second lake in the head of the valley. 

Former extent of the ice in Belly River Valley. — There are several 
other small glaciers in the heads of tributaries to the Middle and 
North Forks of Belly River Valley, last remnants of the great Belly 
River Glacier. 

From an examination of the valley and of the deposits therein 
north of the international boundary it is known that at the last stage 
of the Glacial Period Belly River Valley was occupied by a great 
glacier extending from the Continental Divide northeastward across 
the international boundary into southern Alberta, a distance of at 



GLACIERS OF GLACIER XATIOXAL PARK. S7 

least 30 miles (see map facing p. 32). Xo detailed study of the 
glacial phenomena has yet been made throughout this vaUey and its 
several tributaries, but there is reason for thinking that at a pomt 3 
miles south of the forty-ninth parallel, or 10 miles from the Conti- 
nental Divide, the ice m the vaUey was at least 800 feet thick. 

GLACrERS IN THE NORTHWESTERN PART OF THE PARK. 

Vulture PeaJc Glaciers. — An mterestmg area of glaciers and glacial 
phenomena is accessible either from a camp site in the upper 
part of Little Kootenai Creek YaUey or from one at the head of the 
South Fork of Valentine Creek. From either site one can reach the 
top of the ridge between these two valleys by trail and go thence 
west over the divide. A somewhat more difficult and: precarious 
climb may be made up along the face of the cliffs on either the north 
or the south side of the lake at the head of Little Kootenai Creek to 
the notch in the divide, from wliicli the glaciers on the east slope of 
Vulture Peak are easily reached. The latter courses, however, are 
not to be recommended to inexperienced tourists. Between Vulture 
Peak and the ridge on the east is a considerable bench or rock floor 
whose relations suggest that it is part of the floor of an old cu'que 
developed by a glacier in the Quartz Creek Valley from which the 
south wall was cut away by the headward stoping of glaciers which 
occupied Little Kootenai and Logguig Creek Valleys. Three small 
lakelets occupy basins in this rock floor, and on the mountain slope 
to the west are the glaciers. The upper and larger one occupies two 
or more levels. The upper part has a steep surface and is much 
crevassed, and it extends down to the crest of a cliff and pushes its 
drift over to fall to the bench below. Farther south a narrow and 
much crevassed portion of the ice extends down over the cliff to that 
part of the glacier which spreads out on the bench around to the 
east. This part extends to the crest of a lower cliff or ledge and 
thrusts its load of drift over to faU below. The surface, especially 
near the front, is much broken by transverse and longitudinal crev- 
asses. A morainal embankment extends from the foot of the ledge 
to the northwest side of the upper lakelet, showuig that the ice has 
been more extensive. Below the south end of the ledge a separate 
tiny glacier extends down to the water m the upper httle lake. The 
drainage from these glaciers is tributary to Quartz Creek. 

On the ledges just east of this body of ice there is a fine display of 
the results of glacial abrasion in the form of smoothing, poHshmg, 
striatuig, and grooving (fig. 22) . This is to be seen both on northeast- 
dippmg rock surfaces and on vertical jomt faces. L^pward-curvhig 
striae show where the ice rode up over ledges which projected in its 
path. 

Farther south at the foot of the northeast slope of the mountain 
spur Hes another small glacier. This is unique in that the water 



38 



GLACIERS OF GLACIER i^ATIONAL PARK. 



from the northern part escapes across the upturned rock ledges and 
finds its way to and over the chff at the head of Little Kootenai 
Valley, thus bemg tributary to Hudson Bay. The water from the 
southern part of the glacier flows southeastward along the strike 
behind a rock ridge and finally plunges down the cHffs at the head 
of Logging Creek Valley and becomes tributary to Columbia River 
and the Pacific Ocean. Because of this relation the proposal has 
been made to call this Two Ocean Glacier. Strige on the ledges in 
front of this glacier show that it was formerly larger, and extended 
southeastward to the saddle between the heads of Little Kootenai 




Fig. 22. — Glacial grooves, Vulture Peak. 

Photograph by M. II . Campbell. 

and Loggmg Creeks. The southerly trend of stride in this saddle 
indicates that the ice joined a great Logging Creek glacier. 

From the crest of the southeast spur of Vulture Peak there is a fhie 
view of Vulture Glacier, which hes in an upper cirque in the south 
side of the mountam mass more than 3,000 feet above the lakes in 
the head of Logging Creek Valley. From the notch in this creek one 
can easily reach this glacier. The glacier and neve have a ^\idth 
from southwest to northeast of about four-fifths of a mile and a length 
from northwest to southeast of about seven-eighths of a mile. From 
the neve at the back the ice descends with a slope of 15° to 20°, which 
increases rapidly toward the front where several lobes cascade doAvn 
over the ledges into notches in the lip of the upper cirque. The total 



GLACIERS OF GLACIER NATIONAL PARK. 39 

descent from the gaping bergschrund near the top of the neve slope 
to the end of the lowest lobe is 1,000 feet or more. The surface of 
the ice is smooth and banded from side to side with soiled zones 
marking the outcropping of the glacial strata. 

That part of the glacier south of the end of the bifurcating ledge 
is so broken by crevasses as not to be readily crossed. 

In places there are morainal deposits some distance below the ends 
of the frontal lobes. One of the small lobes has been considerably 
larger, as shown by the fact that there is a lateral moraine lying on 
a bench 50 or 60 feet higher and several rods farther south than the 
edge of the ice. The front slope of this lobe is about 27°. 

On August 27, 1913, several attempts were made to measure the 
rate of ice movement. Not far from the end of the main lobe a spike 
was set in the ice at 2.30 p. m., 26|- inches in advance of a mark on 
the underlying rock. At 3.30 p. m. the distance had increased to 
26 f inches, an advance of one-half inch in one hour. Markers set at 
the northeast side of the same lobe several hundred feet higher up 
showed no advance between 2.20 and 3.35 p. m. of the same day, 
thus indicating retardation of movement at the side of the lobe. 
Markers set at each side of the ledge which projects through the ice 
showed no appreciable advance between 1 and 2 p. m. of the same 
day. Evidently the flow lags about this ledge just as the recurved 
dirt bands seem to indicate. Near the southeast end of the ledge 
which bifurcates the glacier, markers were set at 1.30 p. m. on this 
day, and when reexamined at 2 p. m. the ice had moved one-half 
inch. 

Carter Glaciers. — On the upper slope at the head of Valentine Creek 
near Jefferson Pass are two small glaciers designated the Carter 
Glaciers, in honor of the late Senator Carter of Montana. The most 
southerly one is about one-fourth mile in extent from back to front 
and about three-fourths of a mile wide from northwest to south- 
east. The surface is smooth and shows but few crevasses. Though 
so small a glacier, the front is bordered by a morainal embankment 
rising in places 50 feet above the ice on the inside and 100 feet 
above the rock on the outside. The ice front has, in part, been melted 
back 200 feet from the summit of the ridge, but elsewhere it is pressed 
snugly against the moraine. 

A short distance farther north there is a somewhat larger compound 
glacier consisting of a lower main body, much crevassed because of 
the steepness and irregularity of slope, and two distinct smaller ones 
higher up on the cliff. The upper glacier cascades down to the lower 
one. Along the north front of this is a strong moraine with reliefs 
of 60 to 70 feet on the inside and 80 to 100 feet on the outside. At 
the center of the front the ice thrusts its load of drift over the crest 
of a 50-foot cliff. The height and position of the moraine on the north 



40 



GLACIERS OF GLACIER NATIONAL PARK. 



side indicate that at some time tlie glacier has had considerably 
more bulk than it now has. 

On the north slope of Mount Carter is a small glacier more resem- 
bling the valley type in that it extends through the contracted open- 
ing of the cirque and cascades down the steep slope in a long, narrow 



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tongue. The ice has shrunken away from its strong lateral moraine. 
At the front of the cascading tongue the drift is dumped down the 
steep slope. It is this glacier which furnishes most of the glacial 
silt which renders so milky the South Branch of Bowman Creek 
as seen from the trail leading to Brown Pass. 



GLACIEKS OP GLACIER NATIONAL PARK. 41 

Rainhow Glacier. — From the mountain ridge east and north of 
Vulture Peak there is a fine view across the head of Quartz Creek 
Valley to the Rainbow Glacier nestling in an upper cirque which 
scallops the mass of Cerulean Ridge on the east flank of Rainbow 
Peak (fig. 23). 

This glacier and its neve has a breadth from northeast to southwest 
of nearly 1 mile and a length from northwest to southeast of 1^ miles. 
The entire lower half is much crevassed as though it were moving 
down over a steep and irregular slope broken by steps or ledges. The 
maximum descent of the ice is about 2,000 feet. At about the 
middle of the front of the glacier a tongue about 100 yards vdde 
extends by cascading down to a ledge about 200 feet below the main 
front. Excepting in the south part, where a moraine embankment 
borders the ice, the glacier crowds forward to the very verge of the 
cliff. The ice in places seems to overhang the edge, and abrupt ice 
cliffs suggest that great masses of ice break off and are precipitated 
to the abyss over 2,000 feet below. 

Olson Creek glaciers. — Looking southward from Brown Pass one 
sees in the great upper cirque a glacier which has a width of nearly 
seven-eighths of a mile and which descends about 1,200 feet or more 
in the three-fourths mile of its length. This may be reached by an 
easy climb of a few hundred feet from the pass. When somewhat 
larger than it was when seen by the writer in August, 1913, this glacier 
pushed its terminal moraine near the crest of the cliff which drops to 
the head of the valley below. Since that time the ice has shrunken 
somewhat from the moraine. More or less detached portions of the 
glacier lie on benches in the cirque wall above the main mass. Near 
the front the ice is broken by crevasses, some of which are 10 to 15 
feet wide at the top and 15 to 20 feet deep. In the walls of these 
crevasses the banding of the ice is seen to dip backward upstream at 
low angle. The ice exposed here carries little or no included drift. 
At one point where the foot of the glacier is just at the top of a ledge 
the ice rides free a foot or so above the rock for a distance of at least 
25 to 30 feet back from the margin. Looking into this space one sees 
but little drift in the bottom of the ice. Where the ice is grinding 
polishing, and scoring the rock ledges there appear, so far as can be 
seen, to be but a thin layer of fine rock flour and small fragments 
between the clear ice and the rock surface. 

These and other small glaciers in the cirques farther east are the 
only remnants of the great glacier which during the last great exten- 
sion of the ice occupied Olson Creek Valley and was tributary to the 
one in Little Kootenai Creek Valley. To this were also tributary 
the glaciers occupying the head branches of this valley and the val- 
leys of Valentine and Boundary Creeks. It is known that at the last, 
or Wisconsin, stage of glaciation this great trunk glacier extended 
northward into southern Alberta. Ten or twelve miles north of the 



42 



GLACIERS OF GLACIER NATIONAL PARK. 



boundary line the deposits of this glacier pass under those of the great 
continental ice sheet. Observations of glacial striae high upon ihs 
mountain slopes at the head of Waterton Lake indicate that the ice 
was at least 1,500 feet thick opposite the mouth of Olson Creek and 
it was probably even thicker than this. 

Boulder Glacier. — Looking westward from Brown Pass across the 
great cirque at the head of Bowman Creek Valley, one sees, high up 
at the top of the great cirque wall, two small glaciers. The larger 
one of these is Boulder Glacier (fig. 24) . This may be reached from 
the pass, but the route is somewhat hazardous and is not to be recom- 
mended for inexperienced climbers. The bench on which this glacier 
rests is formed by a lava bed. This rock emierges from beneath the 




Fig. 24. — Boulder Glacier, Kintla Peak in background. 
Photograph by W. C. Alden. 

eastern margin of the ice and extends thence to the crest of the wall 
of the lower cirque. In this interval there is a remarkable exhibi- 
tion of the effects of glaciation produced when the ice had a some- 
what greater extent. The ledges are scored with striae and so 
smoothly rounded and polished as to offer in many places precarious 
footing (fig. 25). The glacier extends westward through the gap in 
the mountain crest. The disposition of the zones marking the strati- 
fication and also the general surface slope indicate that the ice now 
moves toward the cliff on the north side of the gap. For a short dis- 
tance in the midst of the gap there is a strong morainal embankment 
piled 25 to 35 feet high near the foot of the mountain ridge on the 
north. This moraine, which is composed of intermingled rock flour 
and partly worn and partly angular rock fragments ranging in size 
from a fraction of an inch to 6-foot blocks, is continuous around the 



GLACIERS OF GLACIER NATIONAL PARK. 



43 



west side of the mountain ridge and also about the western part of 
the glacier. 

Emerging from beneath the western part of the glacier the lava 
bed extends westward and northward as the floor of two broad gaps 
until it is cut off at the crests of the walls of two lower cirques in 
which head branches of Kintla Creek. The surface of this uneven 
textured, vesicular rock is finely glaciated, exhibiting striae, gouges, 
and beautifully rounded and pohshed roches moutonnees. 

Boulder Glacier, together with four tiny glaciers in scallops high 
up in the walls of the great cirques farther southwest and the cascad- 
ing glacier on the northeast slope of Mount Carter, are the only rem- 
nants of the great glacier which once occupied the vaUey of Bowman 




Fig. 25.- — Glaciated lava bed in front of Boulder Glacier. 
Photograph by W. C. Alden. 

Creek and Lake. On the north slope facing the lake, opposite Rain- 
bow Peak, the writer observed horizontal glacial striae evidently pro- 
duced by the great valley glacier 1,100 feet above the lake. The lake 
opposite this point is 150 feet deep, so that it is known that the great 
valley glacier must have had a thickness of at least 1,200 or 1,300 
feet opposite Rainbow Peak. 

AGASSIZ AND KINTLA GLACIERS. 

From the mountain slope west of Boulder Glacier one gets a dis- 
tant view of Agassiz Glacier, one of the finest in the park, on the 
northeast slope of Kintla Peak (fig. 26). This glacier has a breadth 
of 1.3 miles. From the broad main part of the mass a narrow 
tongue extends nearly 1,200 feet lower down the slope. This gives 
the glacier a length from southwest to northeast of 1.8 miles. The 



44 GLACIERS OF GLACIER NATIONAL PARK. 

ice in this lower tongue is much crevassed. West of this lobe a mo- 
rainal embankment borders the ice. Agassiz Glacier has a vertical 
extent of about 2,000 feet, the lowest point being about 5,800 feet 
above sea level. The glacier is said to be accessible from Upper 
Kintla Lake. 

On the opposite, or west, side of Kintla Peak is Kmtla Glacier 
(fig. 27), having a breadth of more than 2 miles, but an area about 
the same as Agassiz Glacier. 

EARLY GLACIAIi HISTORY OF THE REGION. 

Wisconsin stage. — In the above descriptions of the glaciers of the 
park reference has been made to former greater extension of the ice. 




Fig. 26. — Kintla Peak and Agassiz Glacier. 
Photograph by W. C. Alden. 

The geological studies in and adjacent to the park have developed 
evidence that there were at least two and possibly three different 
times when the glaciers extended far dowm the vallej^s and out onto 
the neighboring plains. These extensions of the mountain glaciers 
were probably contemporaneous w^ith the development and deploy- 
ment of the great ice sheets which covered so large a part of the 
North American Continent durmg the several stages of the Glacial 
Period, or the Great Ice Age. As is the case m the study of the phe- 
nomena of the continental ice sheets, so also the study of Kocky 
Mountain glaciation has developed evidence showmg that the epochs 
when climatic conditions were such as to cause ^great extensions of 
the glaciers alternated with epochs when conditions were similar to 
those of the present so that the glaciers melted away and the valleys 
were occupied as now by streams. 



GLACIERS OF GLACIER NATIONAL PARK. 



45 



On the map facing page 32 an attempt lias been made to repre- 
sent graphically conditions as they were in the mountams and on the 
plains east of the park during the maximmii of the last great stage, 
known as the Wisconsm stage, of glaciation. On this map the momi- 
tain valleys are shown filled with ice 1,500 to 2,500 feet thick, the 




O r:^ 



glaciers headmg in the many cirques and extending thence down the 
valleys and out onto the plains. The crests of the dividmg mountain 
ridges are represented as bare, although they were probably m reality 
more or less mantled with snow and ice. The map shows the general 
relations of the mountain glaciers to the border of the great Keewatin 
glacier which centered on the Keewatm plateau v.^est of Hudson 



46 GLACIERS OF GLACIER XATIOXAL PARK. 

Bay, and also the temporary lake, Cut Bank glacial lake, which re- 
sulted from the blockmg of Cut Bank Creek by the ice. 

Streams of ice heading m the mountain valleys now drained by 
Two Medicine and Badger Creeks and then- tributaries coalesced and 
spread out on the plain as a great piedmont glacier, known to geolo- 
gists as the Two Medicine glacier. This glacier had a maximum 
length of about 48 miles and a breadth of 30 miles. The knolled and 
pitted surface of its morainal deposits may be seen between the rail- 
way and the flat-topped ridge 5 miles north of Glacier Park station. 
North of this, ice m Lake Creek Valley coalesced with a glacier in 
Cut Bank Valley. Moramal deposits of these glaciers are crossed by 
the automobile road leadmg from Glacier Park station to St. Mary 
Lakes. 

St. Mary Valley was occupied by a great trunk glacier which so 
nearly filled the valley where the lakes now lie that it deposited a 
well-marked lateral morame at the top of the ridge on the east 1,200 
foot or more above the lower lake. So effectually did this ridge serve 
as a diverting dam that the greater glacier, instead of extending 
directly eastward onto the plams, was turned northward mto south- 
ern Alberta. TVhere the ridge is lower, east of Babb, the ice did 
extend onto the upland, and a lobe deposited a strongly marked 
moraine, enclosing the basins of Duck and Goose Lakes. In St. 
Mary Valley about 1 mile south of the boundary the drift of the 
St. Mary Glacier, which is composed entirely of material from the 
mountams, is overla^^ped by drift of the contmental, or Keewatm, 
glacier, which contams granite boulders from the region of Hudson 
Bay. Tributary to St. Mary Glacier were glaciers in the valleys of 
Kennedy, Swiftcurrent, Boulder, Red Eagle, and Divide Creek Val- 
leys. 

Drift of the glaciers which at the same time occupied Belly Biver 
and Waterton Lakes valleys is also overlapped by drift of the conti- 
nental glacier, in the one valley about 9 miles and hi the other about 
12 miles north of the international boundary. 

The phenomena in the western part of the park indicate that the 
valleys of Kintla, BoT\TQan, Quartz, Anaconda, Dutch, and Camas 
Creeks and those farther south were also occupied by great valley 
glaciers during the Wisconsin stage of giaciation. The actual ex- 
tent of these glaciers has, however, not yet been fully determined. 
Terminal moraines have been found in Bowman, Quartz, and Ana- 
conda Creek valleys, but it has not been determined that those seen 
farthest downstream mark the limit of extension of the glaciers at 
the Wisconsin stage. The best examples of these deposits are the 
moraines crossed by the trail below Bowman Lake and above and 
below Middle Quartz Lake. 

The great intramontane basin which is represented by West Flat- 
top, Flattop, and Granite Park and similar tracts, and into the bot- 



GLACIEES OF GLACIEE NATIOis^AL PAEK. 47 

torn of whicli are cut the valleys of McDonald and Mineral Creeks, 
is believed to have been occupied by a great central mass of ice 
which discharged principally southwestward by the McDonald 
Creek Valley. 

To this stage of glaciation was probably due some deepening of 
the previously-existing stream-cut valleys and the broadening and 
smoothing of sharp V-shaped cross profiles, produced by stream 
erosion, to the wider and beautifully rounded U-shaped profiles 
now seen {G.g. 1, A and B). Also most of the excavation of the 
remarkable cirques which scallop the slopes of the great mountain 
masses was accomplished at this stage. 

Pre- Wisconsin glaciation.- — The Wisconsin stage of glaciation was 
preceded by a long period during which the glaciers were probably 
absent or much reduced in size, a time during wliich the streams 
were actively engaged in sculpturing the great mountain mass, in 
deepening the valleys, and in eroding .and washing away the soft 
rocks underl}T.ng the adjacent plains. 

Prior to this period of valley cutting, the plains bordering the 
mountains on the east were in general some hundreds of feet higher 
than at present and not so much broken by hills and valleys. In 
the area between the Great Northern Railway and the international 
boundary there are numerous remnants of the former high levels of 
the plains. These are the flat tops of the ridges wiiich stand between 
the several branches of Mlk River, St. Mary River, and Cut Bank 
Creek (the stippled tracts shown on the map facing page 32). Ex- 
amination of the deposits which underlie these flat tops and which 
overlie the upturned and beveled edges of the sandstones and shales 
forming the bulk of the ridges shows that a large part at least are of 
glacial drift derived from the mountains. The relations show that 
long ago, before the valleys which now separate these ridges were 
eroded and when the various remnants yet formed a continuous, 
nearly flat plain, there was a stage of glaciation when the ice heading 
in St. Mary Valley and the tributary valleys was not diverted north- 
ward by St. Mary Ridge and the great trough in which the St. Mary 
lakes and river now lie, but that the tributary glaciers united in a 
great piedmont glacier, which spread directly eastward onto the 
uneroded plain. Ice from Cut Bank and Two Medicine Valleys 
probably also joined in this extension. Over a large area south of 
the railway, however, no remnants of these early glacial deposits 
have been found. They were probably almost entii^ely rem.oved 
during the long interval when stream erosion was going on or were 
obscured by being overrun by the great Two Medicine glacier of the 
Wisconsin stage. 

In places, as, for instance, on the ridge north of Lower Two Medi- 
cine Lake and on St. Mary Ridge, the long exposure of this old drift 



48 GLACIERS OF GLACIER XATIOXAL PARK. 

to the weather has resulted in the limestone pebbles and bowlders 
being removed from the upper part by solution and the calcium car- 
bonate being carried down by the percolating waters and deposited 
as a cement, binding the lower part of the drift into a hard con- 
glomerate. 

The relatively great age of this early glacial drift may be inferred 
from the fact that even those tributaries of Milk River wliich received 
none of the mountain water have cut valleys several miles in width 
and hundreds of feet deep below the horizon of the former high-level, 
drift-covered plains. It is believed that St. Mary Valley was deep- 
ened at least 800 or 1,000 feet during the interval between the earlier 
and the Wisconsin stages of glaciation, that the tributary mountain 
gorges and other valleys were correspondingly eroded, and that a 
considerable part of the sculpturing of the great mountain mass was 
accomplished during tliis period of stream activity. Compared with 
the time which has elapsed since the Wisconsin stage of glaciation 
the interval of deglaciation must have been very long. 

In the above discussion the pre-Wisconsin interval has been 
referred to as a single uninterrupted epoch of deglaciation and ero- 
sion. There is, however, definite evidence that it was not such. 
There are, east of the mountains in the Blackfeet Indian Reservation, 
remnants of three sets of plains above the levels of the present drain- 
age lines, all of these older than the drift of the Wisconsin stage of 
glaciation, and on two of these are deposits of pre-Wisconsin glacial 
drift. The third set of these plains comprises the broad valley bot- 
toms, onto which the glaciers of the Wisconsin stage encroached and 
into which the present streams have cut their sharp narrow channels. 

It is thus probable that there were two distinct earlier stages of 
glaciation of the mountains separated from each other and from the 
Wisconsin stage by long intervals of deglaciation and stream erosion. 
Some of these stages may have resulted from or have been accom- 
panied by general elevation or depression of the region. 

Within the limits of this brief paper there is not opportunity to 
discuss all the evidence bearing on this question. For further 
details reference should be made to other papers by the present 
writer and others.^ 

1 Pre-Wisconsin glacial drift in the region of Glacier Kational Park, Mont., by AVm. C. Alden, Bull. 
Geol. Soc. Am., vol. 23, pp. 687-708, 1912. 

Ditto, by Wm. C. Alden and Eugene Stebinger, Bull. Geol. Soc. Am., vol. 24, pp. 529-572, 1913. 

The Montana lobe of the Keewatin ice sheet, by F. H. H. Calhoun, Prof. Paper U. S. Geol. Survej-, No. 
50, 1906. 

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